Chiral gauge models for light sterile neutrinos

We construct a family of simple gauge models in which three sterile neutrinos become naturally light by virtue of a generalized seesaw mechanism involving a chiral gauge symmetry. Examples where the chiral gauge group is $\mathrm{S}\mathrm{U}(5{)}^{\prime }$, $\mathrm{S}\mathrm{U}(7{)}^{\prime }$, $\mathrm{S}\mathrm{U}(3{)}^{\prime }$ and/or their descendants are presented. A unified model based on $\mathrm{S}\mathrm{O}(10)\times \mathrm{S}\mathrm{O}(10{)}^{\prime }$ which embeds many of these models is constructed wherein three light sterile neutrinos are just as natural as the three ordinary neutrinos. These gauge models have relevance to current neutrino oscillation data, including the LSND anomaly.